Pitch changing mechanism



G. J. SMITH-PERT ETAL FITCH CHANGING MECHANISM Dec. 28, 1948.

v5 Sheets-Sheet 1 Filed Feb. 8, 1945 www,

Dec. 28, 1948. G. J. SMITH-PERT ETAL 2,457,609

/PITCH CHANGING MECHANISM l Filed' Feb. a, 1945 V 5 sheets-snaai;

G. J. SMITHPERT E'I'Al..v

` P I'ra CHANGINGMECHANQM Dec. 28, 1948.

Filed Feb. s, 1945 '5 sheets-sheet -s @M QMRQMM Dec- 2.8, 1948- G. J. SMITH-PERT x-:TAL 2,457,609

- FITCH CHANGING MECHANISM Filed Feb. 8. 1945 '5 Sheets-Sheet 4 ...lllllllll Patented Dec. 28, 1948 PI'ICH CHANGING MECHANISM George James Smith-Port and Archibald Graham Forsyth, Cheam, England, assignors to The Fairey Aviation Company Limited, Hayes, England Application February 8, 1945, Serial No. 576,740

6 Claims.

This invention relates to variable pitch propellers.

In light weight, two bladed propellers, it is desirable to provide a simple, light weight, reliable arrangement for changing the pitch of the blades between fine and coarse pitch. It is a principal object of the invention to provide such an arrangement.

Light weight two ibladed propellers are frequently provided with counterbalance weights. These are sometimes in the form of segment shaped plates disposed in parallel planes at the bases of the blade sockets and tangential to the propeller drive shaft. In accordance with the present invention, such counterbalance weights are employed as a part of the pitch changing arrangement in such a manner as to effect a long moment arm for the turning movement. It is an important object of the invention to accomplish such results. 4

The invention employs movement of the counterbalance weights to effect a pitch changing movement from, say, fine to coarse, and employs a piston actuated by oil under pressure, either from the engine lubricating system or from a separate source, for moving the counterbalance weights in the opposite direction and consequent- 1y for returning the propeller blades to ne pitch position.

These and other objects of the invention will become more apparent from the following description and claims and accompanying drawings, in which:

Fig. 1 is a longitudinal vertical section (with some parts in elevation) of one embodiment of the invention;

Fig. 2 is a front elevation of the same;

Fig` 3 is a top plan view with one detail being shown in section;

Fig. 4 is a side elevation, partly in section, of one of the elements of the pitch changing mechanism;

Fig. 5 is a front end view of the same element;

Fig. 6 is a front end view of another embodiment; l

Fig. 7 is a longitudinal vertical section, (with some parts in elevation) of the modification illustrated in Fig. 6; and

Fig. 8 is a front end view of further modification.

In Fig. l the tubular propeller drive shaft I is shown as extending forwardly from the engine I i. Threadedly mounted on the drive shaft I0 as at i2 is a sleeve member I3 forming part of the oil pressure means which will be later described. v

The propeller hub I4 is disposed on the propeller drive shaft I0 forwardly of the sleeve I3. The hub i4 is secured in the usual manner by the rings I and I6. The forward ring I8 is provided with a flange I1 having an annular inwardly projecting portion I8 which is disposed in an annular groove I9 in the tubular member 20. The tubular member 20 is threadedly secured on the front end of the propeller drive shaft I 0. One or more pins 2| extend outwardly through holes 22 in the propeller drive shaft I0 and through slots 23 in the tubular member 20 to lock the member 20 with respect to the drive shaft I0. The tubular member 20 has a circular flange 24 provided With a series of holes 25 near its outer circumference.

The propeller hub I4 is formed with tubular castings 26 which, through the sleeves 21, support the tubular sockets 28. Base members 29 to which the blade roots are secured by means of long screws, are mounted for rotary movement within the sockets 28;

The propeller hub structure I4, 26, carries two counterbalance weights 3I and 32, each of which is comprised of a fairly thick plate generally of segment shape in plan. The plates are integral with or secured to rings 33 which extend respectively about the tubular castings 26.

As shown in Figs. 1 and 3, the counterbalance weights 3|, 32 are secured to the base members 29 by means of bolts 34 which extend through slots 35 in the tubular castings 26 and thence int the base members 29.

From Fig. 3 it will be noted that each plate .of the counterbalance weights 3 I, 32 is provided with a cutout 36 to provide easy access to the bolts 34. Also, thevperipheral edges of the plates'areprovided with a notch 31. These notches 31 are engaged by the arms 38 (Fig. 2) which extend radially from a tubular sleeve element 39. It will be noted from Fig. 1 that the sleeve element 39 is disposed concentrically within the vtubular member 2D. It is, however, mounted for relative rotary movement with respect to the latter.

Secured at the front end of the unit is a cap member 40 having an inwardly extending tubular spring receivingportion 4I. The cap member 40 is secured by means of nuts 42 which engage bolts 43 extending from the spacer ring 44. The spacer ring 44 has lateral lugs 45 and bolts 46 pass through slots 41 therein and through the holes 25 in the flange 24 of the tubular member 20 to which the bolts are secured.

Mounted for axial sliding movement Within the hollow propeller drive shaft IIJ is a piston havin-g a head 48 and a forwardly extending tubular body 49. The forwardend of the body is adapted to move within the annular space formed between the concentrically separated sleeve member 39 and the tubular spring receiving portion 4I of the cap member 4I).

As shown in Figs. 4 and 5, the forward end of the piston body 49 is enlarged and is provided on its outer surface with a number of spiral grooves 50. The inner surface of the sleeve member 39 is provided with complementary ribs 5l (Fig. which engage iin Lthe grooves F5B.

The inner surfacefo'f the front 'endlo the piston body 69 is formed with grooves 52 disposed parallel to the axis of the body (Figs. 4 and 5) and these grooves 52 are engaged by `oom-pleinen tary ribs 53 (Fig. l) on the outer 'surface othe tubular spring receiving .portion M :of fthe Icap member 4D. p

A coil spring 54 bears at one yemi against v'the head 48 of the piston and at its other end is disposed in the spring receivingipontionfl andbears against the cap member 40. From Fig.2 it Will be seen that the flangev 24 of the tubular 'member 20 is provided with forwardly extending lugs 55, B. .'lfhes'eflugs are '-.threaid'ed lv'to receive stopbolts 51, 558. JLock nuts 159, 160 are provided. 'Ilhefstop "bolts f'l, A58 .are Aemployed to limit the 'movement 1'offthezarm38.

-Means is provided for `.introducing nil under pressure "to the inter'ior of the hollow 'propeller drive shaft im. .Reference has already been made to the 'sleeve yI3 forming J"a part fof su'ch means. This sleeve l 3, as indicated, iis 'fthreade'dly mount- -edfonthe'drive-shaftil ttorotate therewith. The A' .-sleev'e t3 'is formed y'with an inner annular igroove .51 which Icbmmunicates 'with fa lhole 6,2 lin the drive sha-lit im. The 'sleeve I3 'is-:also provided with an outer 'annular gro'ove S63 :and an oblique 'passageway 161i connects the grooves iBl .and 163.

Mounted on the sleeve l-3 1in :surrounding :relation thereto lis a rin-g fmember fwhien, however, is :separated Pfrom Ythe sleeve .by a stationaryitubu- Ala'r .member 6-5 .Shaving an outward Yflange y-at its forward end.

'lh'e .ring .member 65 'is stationary with respect to the engin-e 4and provided f.with :fanii-niet oil passage 26'7 adapted ito be connected Withasource of 'oil 'under pressure -(not fshown). Also @connectfing 'with passage is an fannu'lar groove "68 .formed lin the ring member .65. 'The tu'bular member 66 has an -openngll whichfoonnects y'the :groove '618 of the ringrmemberfand the 'groove B3 of the sleeve 1.3.

4 head 48 and forces the piston forwardly against I-the faction of spring 54 to the position shown in Figs 1 l'and Because .of the spiral grooves `on the piston Abody -ll`9 and .the complementary ribs 5l on the sleeve .3.9, lthe sleeve will be given a rotary turning movement as the piston moves forwardly. The arms lintelgral vWiththe 'sleeve 39 also move and since their ends are engaged in the notches 31 in the Vcount-orbz't'la'n'oe"Weights 3|, 32 (Fig. 2), the latter will be rotated. this manner ythe pitch of the :blades 'is y.tiring returned yto ne pitch position. Such return pitch changing movement is limited bythe'stop bolt 58.

The arrangement 'operates in lthe following 1 manner.

The pitch of 'the vor'ol'ieller bla/'des upon starting is .ne fpitch {posi-tion. After the :climb Ithe :speed of rotation of fthe propeller hub will l'infcrease .and l`the centrifugal torce resulting will cause the eoounterbalance Weights 3|, .32 :to move @toward the plane of rotation of the blafdes. 'Since the #oounterbalance 'Weights are .secured to the :blade roots, such movement of :the oounterbal- .ance IWeights vvv-ill -econsequently chan-ge the pitch 'When .it )becomes .necessary to return the blades to pitch `lllo'sition, irrespective yof `the amount fof .bentrifugal force, such .pitch 4changing move- .ment is .effected by .introducing oil under pressure 'into Vthepassage '67 Nin the ring'member i65. y

This oil enters groove 68, passes through the opening 69 int-o groove 63 of .the sleeve I3 and fthen through the oblique passage ".64 to the groove 6l and finally through thehol'e 62 to the interior `of the propeller drive .shaft fr0. y"Ihe oil .pressure 'Within the drive shaf-tbears against the piston Adjustment for proper pitch change may be made when the :unit is installed by reason of 'the slots l and also the selection of holes I25 throu-gli which `the bolts f4.6 pass.

The embodiment .illustrated in Figs. 6 and 'luis lquite similar'to-that illustrated in Figs. 1 to 5.,'inelusive. in this embodiment the -hollow propeller :drive shaft 'T9 supports :a propeller hub casting having a central portion 'H surrounding the propeller shaft and which is keyed to rotate 'therewith. It Ais `secu-red again-st longitudinal movement by the 'rings .752 .and 1:3. .The hub casting also has lt'wo .radially extending tubular portions M. 'Threaded Within ithes'e portions y'l -are fthe 'inner supporting-sleeves 15. y

Surrounding ithe ihub 4eastir-ig portions lfd are 'tubular blade .supporting 'membersl le which support the blades 216 rbymeans of .bolt-s. Thesezsup- 'porting members 'F126 are mounted 'by 'the .bearings @18, "T9 .ff-or free Arotation aboxitfthe axis of .the :hub casting portions 14.

'The tubular Alolaiie ysupporting ymembers are each t'hreac'ied to rings 580, and Iieaoh 'c arri'es :asegmerrt `shaped-icmm1;erlo-alance weight 81,282. The edge portions of the Weights are provided with vbevel lgear portions Iv53, 28T# ('see :also Fig. 17). `The bevel gear portions F83, "84 are engaged respectively "by Fbevel Ygefar sections 85 and d6 Ion the lends `vof the arms F61 and 18B carried by for integral with a ring member 89.

'The ring lmember ISB 'is mounted on a. tubular menfiber 790 which iis `4coaxial with the propeller l'drive shaft '1B and extends fforwardly thereof. The outer surface of -the tubular member tu has spiral tgrooves similar to those illustrated in Figs. 4 and "5 of the irst embodiment. 'The iin'nerJsurface of the sleeve 89 has ribs Whichen'gage insaid spiral grooves.

The `propeller drive shaft To, near Eits trout send, is threaded to receive a tubular member lll, 'fthe latter having an lannif-lar 'groove 92 fenglaiged vby a. iange $95 on `rthe 'ring W3. The v'end o'f l.the propeller shaft 1G is .also provided With holes F923, fand fa locking Jpin @5 passes outwardly through tone 'o'f these iholes iand through la "slot "95 in the `xtubular member 9i to lock the latter to the propeller 'drive lshaft lll. i

Threadedly secured 'Within the tubular member 5| is an element 97 having yafcentral bore in which fthe tubular member "9U is `Imounted for longitudinal sliding movement. The tubular member forms ith'e `-body of :a piston having Aa "head 98 disp'o'sedfor sliding movement Within the hollow propeller shaft flf Whichforms 'a cylinder fforthe piston. A fcoil spring -99 "bears against the forward race of the 'head f9'8 and at its #other end l "against a shoulder 1Illu on the element *3l Surround-ing the 'tubular member gli, ffor-wardly lill-2, fN33 see Fig. 4"69 which are secured by the 'bolts im *to the lement fill. A pin fl-D5 -lCFigs 6 and 7) extends through the collar IUI and into a longitudinal slot 106 in the tubular member 98, thus preventing relative turning movement.

It is to be understood that adjustable stops such as those employed in the first embodiment may be oil under pressure from 4,the aircraft engine (or from an independent source, if desired) is introduced into the hollow propeller shaft '10, forces the piston head 98 forwardly. Because of the spiral groove arrangement between the tubular member 90 and ring 89 the latter will be turned as the tubular member 9D moves forwardly and the bevel gears 85, 8E on the arms 8l, 88 will move .the counterbalance weights 8 l, 82 in the opposite direction, thus returning the pitch of the blades to fine pitch position.

Finally, a third modification is illustrated in Fig. 8. This embodiment includes features from each of the other two. In structure and operation it is identical with the embodiment of Figs. 6 and '7 except that the arms 81, 83 instead of having bevel gear portions, are provided with knob ends |88, |09, which are engaged in notches HD, lll in the peripheral edges of the counterbalance weights 8 I, 82. In this latter respect the modification is similar to that illustrated in Figs. l to 5, inclusive.

In all three embodiments, the oil under pressure for moving thepiston forwardly may be supplied through means such as shown in Fig. l, or alternatively, directly from the engine lubricating system. In this latter case the oil from the engine lubricating system will pass directly from the engine into the hollow propeller drive shaft.

It will be understood that the embodiments illustrated are by way of example and that changes in structure and arrangement may be made within the scope of the invention which is not to be limited except as indicated in the following claims.

We claim:

l. A variable pitch propeller for aircraft and the like comprising, a propeller hub mounted for rotation on a propeller drive shaft, said hub having propeller blade supporting members, propeller blades supported by said members for rotary movement about their .longitudinal axes, a segment-shaped counterbalance'plate carried by each of said members for rotary movement about said axes, said platesbeing connected with the propeller blades t turn therewith during pitch changing movement, said plates being disposed in planes parallel to the axis of said propeller drive shaft, a rmember supported forwardly of said propeller drive shaft for relative rotary movement with respect thereto, said last-mentioned member having arm means provided with a gear-portion engaging a gear -on a peripheral portion of each of said plates, whereby said plates upon rotation of the hub will move toward the plane of rotation of the blades and effect a pitch change in one direction, and also move said varm means and said last-mentioned member inI one direction about the axis of the propeller drive shaft, and hydraulic means for moving said last-mentioned member and arm means in the other direction, whereby said plates are returned to their original position thus el'ecting a pitch change to the original pitch position.

2. A variable pitch propeller for aircraft and the like comprising, a propeller hub mounted for rotation on a propeller drive shaft, said hub having propeller blade supporting members, propeller blades supported by said members for rotary movement about their longitudinal axes, a segment-shaped counter-balance plate carried by each of said members for rotary movement about said axes, said plates being connected with the propeller blades to turn therewith during pitch changing movement, said plates being disposed in planes parallel to the axis of said propeller drive shaft, a member supported forwardly of said propeller drive shaft for relative rotary movement `with respect thereto, said last-mentioned member having two arms each of which engages a notch in the peripheral portion of said plates, whereby said plates upon rotation of the hub will move toward the plane of rotation of the blades and effect a pitch change in one direction, land also move said arm means and said last-mentioned member in one direction about the axis of the propeller drive shaft, and hydraulic means for moving said lastmentioned member and arm means in the other direction, whereby said plates are returned to their loriginal position thus effecting a pitch change to the original pitch position.

3. A variable pitch propeller for aircraft and the like comprising, a propeller hub mounted for rotation on a hollow propeller drive shaft, said hub having blade supporting members, propeller blades supported |by said members 4for rotary movement about their longitudinal axes, a segment-shaped counterbalance plate carried by each of said members for rotary movement about said axes, said plates being connected with the propeller blades to turn therewith during pitch changing movement, said plates being disposed in planes parallel to the axis of said propeller drive shaft, a member supported forwardly of said propeller drive shaft for relative rotary movement with respect thereto, said last-mentioned member having arm means engaging a peripheral portion of each of said plates, whereby said plates upon rotation of the hub will move toward the plane of rotation of the blades and effect a pitch change in one direction, and also move said arm means and said member in'one direction about the axis of the propeller drive shaft, and hydraulic means for moving said last vmentioned member and arm means in the other direction, whereby said plates are returned to their `original position thus effecting a pitch change to the original pitch position, said hydraulic means comprising a piston in said hollow tubular drive shaft and a spiral thread connection between said piston and said last-mentioned member, and means for supplying a fluid under pressure to the piston to move it forwardly, whereby relative rotary movement is imparted to said last-mentioned member.

4. A variable pitch propeller for aircraft and the like comprising, a propeller hub mounted for rotation on a propeller drive shaft, said hub having propeller blade receiving members, propeller blades mounted within said members for rotary movement about their longitudinal axes, a segment-shaped counterbalance plate carried by each of said members for rotary movement about said axes, said plate being connected with the propeller blades to turn therewith during pitch changing movement, said plates being disposed in planes parallel to the axis of said propeller drive 'adomos 7 shaft, :a member supported .forwardly of said ipropeller drive shaft for relative `f totary movement with respect thereto, said ,last-mentioned .member having arm means engaging :a .peripheral p ortion 'of 'each :of said plates, whereby 'said `plates .f

lupon rotation h'of the lhub will move toward the plane of rotation fof the 'blades fandiei'ect a pitch change in one direction, V'and also movey .said arm lmear-1s and said last-mentioned member in one direct-ion about the axis Aof the ,propel/ler drive shaft, .and hydraulic: means for moving said last-mentioned member and arm means 'in the 'other direction, 'whereby said plates are returned to their voriginal position thus effecting a pitch change to the original pitch position, said last- :men-tioned 'member having la .hollow hub 4sleeve portion, a tubular Yelement secured to the viront end -of the propeller drive sha-ft .and ,surrounding said hol-low hub .sleeve portion, a Vpiston mounted for axial lmovement within the hollow propeller drive shaft, said piston .having .a .for-ward end portion provided with spiral grooves, theinner surface -of said hollow ihub sleeve portion .having complementary spi-ral "ribs, a cap memberesecured to said tubular element, said cap member having an inwardly lprojecting tubular part disposed within the piston body, said piston body being keyed -to said tubular part against 'turning movement, and mean-s -for supplying-fluid under pressure lagainst said pis-ton -to move it tor-wardly.

5. A variable pitch propeller for aircraft vand the like comprising, a propeller hub 4mounted for rotation on .fa propel-ler ,drive .sha-ft, said .hub having propeller -blade receiving members, propeller ,blades .mounted within said .members .for 'rotary movement `about their longitudinal axes, a segmentush-aped .counterbalanoe plate Acarried lby each of said members for rotary movement about said aired-said lplates being connected with the .propeller blades to turn therewith during pitchichapging .movement,=said plates being disyposed .in planes parallel -to the Aaxis .of said propeller drive shaft, a imembersupported `forwardly of .said lpropeller :drive shaft (forre'lative rotary .movement with res-peet thereto, said .-lastamentioned mem-ber having arm means engaginga ,peripheral portion -of each of said plates, Where- -by said plates upon ,rotation .of the hub will move toward the pla-ne of -rotation of the `blades .and -eliect a ,pi-tch 4cha-nge in one direction, and also .move said arm means and said last-mentioned member .in one direction 'about the axis of the propeller -drive shaft, and .hydraulic means .for .moving :said last-mentioned member and arm means inthe other direction, whereby said plates are returned vto their original .position thus .e'f-

Vf-ecti-ng a pitch .change .to vthe original Apitch positionsaid last-mentioned member having a .hollow hub sleeve portion, .a tubular element se- -cured to the frontend .of the propeller drive shaft Iand .surrounding .said hollow hub sleeve portion, .a .piston mounted for axial movement Within the hollow propeller drive shaft, said lpiston having .a forward end .portion ,provided with spiral grooves, the inner surface. of .said hollow Vhub ysleeve ,portion having complementary spiral ribs, a cap member secured to said tubular element, .said cap member having :an inwardly projedting .tubular part disposed Within the piston Lbody, .said piston body being keyed 'to said tubular part against 'turning movement, and means for supplying fluid under 'pressure against `said piston to move it forwardly, and spring means disposed within the piston body and bearing against fthe cap member for 'urgingthe `piston rearwardly. l

6. :A variable Apitch propeller for iaireraft and the .like oomprising, fa propeller heb for rotation -on .a :propeller ldrive shaft, .hub having: propeller blade .receiving propeller blades mounted within Vsaid members vfiori-Ilotalfy movement about rtheir .iongitudinalaxes 'a sea- ...ment-ishaped -oounterebalance splatter-carried by :each or fsaid members fior rotary movement about said axes, said plates being conneetedfwithithe propeller blades to :turn (therewith during pitch @hanging movement, saidplates being disposed `in .planes :parallel to t'he'axispf :saidpropeller drive shaft, a member supported forwardly. .of said propel-ler drive 'shaft for relative rotary .movement with zrespect thereto, vsaid '1a-stamentioned meinberfhaving :arm means engaging. ia peripheral *portion of leach `of :said plates; viz-here- :by said plates mponrrotation tol the-hub 'will move toward the plane of irritation lof :the :bladeszand leiiect a pitch change in. onerdirection, and'also imove said :arm vnfxraavns :and said .lastementione'd member in one .direction Va'bont 'saisis' of "the .fprop'ell'er :drive fslraaxandlhmrauiic :meansdor .moving said las'thmentioned member-:onderuit means in the other direction-whereby 'said :plates `are "returned to itlneirfori'ginal positionvthus effect-ing a .pitch @hang-'e "to `itlzre original pitch position, fsaid Plast-mentiord having fa .hollowlnob sleeve abortion, atubular element-secured to .the firent end l:of the .propeller drive :shaft and .surrounding 'said :hollow hub .sleeve portion, fa piston mounted 'for :axial movement within the hollow *propeller idr-ive shaft, said pistonhaving fa .toward end portion :provided 'with' l.spiral grooves, ithe Iinner suriiaoe'ldffisaid y hollow hub sleeve portion having'conrplem'entary spiral ribs, a l'cap 'member secured to Vsa'i'd vtlloi-ilar lelement, said fcap member having an "inwardly proj'eotlng tubular .part disposed @Within the piston body, fsaid pis'tonff-bod-ybeing keyed to .said Etabular part against @turning movement, means 'for supplying A fluid under k-pres'stu-'e against vsaid piston to move Zit Ifoutwardly,' and Vmeans VYorjad- ,insti-ngr the initial position 'of sa'id 5arm means,

said adjusting means including a fser'i'e's fof holes f in a flange lintegral with -`said itu'bu'lar 'leme'nt, 'and a pai-r fof slotted lugs carried by said cap member whereby the cap 'member Amaybe 'bolted to said flange in any one of a number fof positions. f fGEGRG-E .SMITH-PERT. f

ARCHIBUD El:GRIS'Y'IYIII.l

'EITEE 'The following references are of 'record in 'the fll'e Of tbl-.S ,pal-tenti STTES R'I'ENTSv 793;'323 virda-noe my, .16,1935 

